r0> enable
r0# config t
r0(config)# interface loopback 0
r0(config-if)# ip address 10.10.10.251 255.255.255.255
r0(config-if)# no shutdown
r0(config-if)# exit
r0(config)# interface fastethernet 0/0
r0(config-if)# ip address 172.18.30.251 255.255.255.0
r0(config-if)# no shutdown
r0(config-if)# exit
r0(config)# router ospf 180
r0(config-router)# router-id 10.10.10.251 0.0.0.0.0
r0(config-router)# log-adjacency-changes
r0(config-router)# network 10.10.10.251 0.0.0.0 area 0
r0(config-router)# network 172.18.30.0 0.0.0.255 area 0
r1> enable
r1# config t
r1(config)# interface loopback 0
r1(config-if)# ip address 10.10.10.252 255.255.255.255
r1(config-if)# no shutdown
r1(config-if)# exit
r1(config)# interface fastethernet 0/0
r1(config-if)# ip address 172.18.30.252 255.255.255.0
r1(config-if)# no shutdown
r1(config-if)# exit
r1(config)# interface fastethernet 0/1
r1(config-if)# ip address 172.18.31.252 255.255.255.0
r1(config-if)# no shutdown
r1(config-if)# exit
r1(config)# router ospf 180
r1(config-router)# router-id 10.10.10.252 0.0.0.0.0
r1(config-router)# log-adjacency-changes
r1(config-router)# network 10.10.10.252 0.0.0.0 area 0
r1(config-router)#network 172.18.30.0 0.0.0.255 area 0
r1(config-router)#network 172.18.31.0 0.0.0.255 area 0
r2> enable
r2# config t
r2(config)# interface loopback 0
r2(config-if)# ip address 10.10.10.253 255.255.255.255
r2(config-if)# no shutdown
r2(config-if)# exit
r2(config)# interface fastethernet 0/0
r2(config-if)# ip address 172.18.31.253 255.255.255.0
r2(config-if)# no shutdown
r2(config-if)# exit
r2(config)#interface fastethernet 0/1
r2(config-if)# ip address 172.18.32.253 255.255.255.0
r2(config-if)# no shutdown
r2(config-if)# exit
r2(config)# router ospf 180
r2(config-router)# router-id 10.10.10.253 0.0.0.0.0
r2(config-router)# log-adjacency-changes
r2(config-router)# network 10.10.10.253 0.0.0.0 area 0
r2(config-router)#network 172.18.31.0 0.0.0.253 area 0
r2(config-router)#network 172.18.32.0 0.0.0.253 area 0
r3> enable
r3# config t
r3(config)# interface loopback 0
r3(config-if)# ip address 10.10.10.254 255.255.255.255
r3(config-if)# no shutdown
r3(config-if)# exit
r3(config)# interface fastethernet 0/0
r3(config-if)# ip address 172.18.32.254 255.255.255.0
r3(config-if)# no shutdown
r3(config-if)# exit
r3(config)# router ospf 180
r3(config-router)# router-id 10.10.10.254 0.0.0.0.0
r3(config-router)# log-adjacency-changes
r3(config-router)# network 10.10.10.254 0.0.0.0 area 0
r3(config-router)#network 172.18.32.0 0.0.0.255 area 0